For 3D gaming the best bet for use with an Nvidia graphics card seems to be the
ASUS VG278H. However, if you would rather have a 24in, then the
BenQ XL2420T is a widely regarded 120Hz and 3D monitor (you can buy the
Nvidia 3D vision2 kit separately or
bundled with the monitor).
Personally, I would only go down the 3D route if you are convinced you will use the technology regularly, as many people don't like using it and it adds a lot of cost.
Also, please bear in mind that a 120Hz monitor which is also advertised as a "3D" monitor can also be used as a 120Hz 2D monitor with any brand of graphics card (eg. that Samsung 120Hz with the GTX 680). So if you don't care about using the 3D then the Samsung S27A750/950 would work fine as a 2D 120Hz monitor with your GTX 680. To be clear, with a 120Hz refresh rate (the standard refresh rate is 60Hz) motion on screen feels smoother, so playing fast paced games can be more enjoyable.
For high-res, the Dell you picked is excellent. The pixel response of this monitor is rather good (so little ghosting is seen), however the input lag is a bit high - this means it isn't ideal for competitive online gaming - but it is certainly usable. Most monitors of this type either have the same "issues" with input lag or inferior motion handling (such as the HP and Samsung 1440p monitors).
That said, the
Hazro HZ27WC doesn't use a scaler, but does use pixel overdrive - so it's pixel response is on the level of the dell, while the input lag is much lower - hence a really nice monitor for gaming (
here is a review). However, the QC and customer sevice offered with the Hazro isn't as good as the Dell - so you have to make your own judgemnt on which to go for.